Hello!
Huh neat. That makes me think like the roads being enchanted to help avoid normal monsters.... looks neat though. Though I am not sure if i should read too much into it, except design choice, but here are the thoughts i immediately had after reading this.
Maybe roads are enchanted per special crystals or whatever that helps repell monsters. Maybe there are portable ones that get rid of monster attacks for X steps? There might be "fake" roads that people made as deathtraps for adventurers, aka bandits being bandits. Maybe with them having an off and on "switch". And so on and forth. Maybe those "switches" are war targets to disrupt deliveries, etc, etc. Could also explain why cities are safe, guards, enchantments, etc.
Well do have a nice day. I am certainly going to look here now and then.